Plant Biology

Testing Darwin’s Competition-Relatedness Hypothesis

Tan Bao, Ph.D.

In The Origin of Species, Darwin argues that organisms that are more closely related will compete more fiercely than those that are less closely related. This relationship has been named the competition-relatedness hypothesis. It has rarely been tested but has been used to explain fundamental ecological and evolutionary patterns such as those of species diversity and coexistence. Recently, this assertion has been challenged with data raising doubts about its generality. Here we show that the competition-relatedness hypothesis is not supported in an experiment specifically designed to test it. We found that genetic relatedness did not explain competitive struggle in a pair-wise competition experiment with 12 ecotypes of Arabidopsis thaliana grown at both low and high nutrient levels.

Characterization of agglutinin domain containing proteins in flax

Kashfia Faruque, M.Sc.

The recent sequencing of flax genome has provided us with tools to gain new insights into this economically important crop, grown mainly for its seed oil and stem fibers. The sequence analysis resulted in a prediction of the presence of 19 agglutinin domain (PFAM PF07468) containing proteins in flax. Agglutinins are carbohydrate binding lectin proteins that are well known defense proteins of plants against insects and pathogens. Interesting fact is that plants like cassava, poplar which are close relatives of flax are not enriched for these proteins. This study was conducted to characterize this protein family of flax and determine their potential function. The phylogenetic analysis with the known lectin families revealed their sequence similarity to the Amaranthin family. Analysis with ‘SignalP 4.0 server’ found no evidence of signal peptides in any of these proteins. Thus they are probably cytoplasmic proteins. These genes were found to be fairly highly expressed in stem, leaves, cotyledons, roots, floral buds and embryos. Tests with hormones also resulted in the up regulation of some of the genes indicating their role in defense against predators and pathogens. Further studies will be conducted in order to determine the function of these proteins in flax.